package com.pkk.spring.cloud.service.gateway.filter.global;

import static org.springframework.web.cors.CorsConfiguration.ALL;

import org.springframework.context.annotation.Bean;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpMethod;
import org.springframework.http.HttpStatus;
import org.springframework.http.server.reactive.ServerHttpRequest;
import org.springframework.http.server.reactive.ServerHttpResponse;
import org.springframework.web.cors.reactive.CorsUtils;
import org.springframework.web.server.ServerWebExchange;
import org.springframework.web.server.WebFilter;
import org.springframework.web.server.WebFilterChain;
import reactor.core.publisher.Mono;

/**
 * 跨域过滤器
 *
 * @author peikunkun
 * @version V1.0
 * @date 2021-01-26 12:01
 **/
public class CorsFilter {


  private static final String MAX_AGE = "18000L";


  /**
   * 跨域的过滤器配置
   *
   * @return org.springframework.web.server.WebFilter
   * @Param
   * @author peikunkun
   * @date 2021/1/26 0026 下午 12:01
   * @since
   */
  @Bean
  public WebFilter corsFilter() {
    return (ServerWebExchange ctx, WebFilterChain chain) -> {
      ServerHttpRequest request = ctx.getRequest();
      if (!CorsUtils.isCorsRequest(request)) {
        return chain.filter(ctx);
      }
      HttpHeaders requestHeaders = request.getHeaders();
      ServerHttpResponse response = ctx.getResponse();
      HttpMethod requestMethod = requestHeaders.getAccessControlRequestMethod();
      HttpHeaders headers = response.getHeaders();
      headers.add(HttpHeaders.ACCESS_CONTROL_ALLOW_ORIGIN, requestHeaders.getOrigin());
      headers.addAll(HttpHeaders.ACCESS_CONTROL_ALLOW_HEADERS, requestHeaders.getAccessControlRequestHeaders());
      if (requestMethod != null) {
        headers.add(HttpHeaders.ACCESS_CONTROL_ALLOW_METHODS, requestMethod.name());
      }
      headers.add(HttpHeaders.ACCESS_CONTROL_ALLOW_CREDENTIALS, "true");
      headers.add(HttpHeaders.ACCESS_CONTROL_EXPOSE_HEADERS, ALL);
      headers.add(HttpHeaders.ACCESS_CONTROL_MAX_AGE, MAX_AGE);
      if (request.getMethod() == HttpMethod.OPTIONS) {
        response.setStatusCode(HttpStatus.OK);
        return Mono.empty();
      }
      return chain.filter(ctx);
    };
  }

}
